1. Field of the Invention
This invention related to resonator systems such as microresonator systems and methods of making same.
2. Background Art
The following references are referenced herein:    [1] Y.-W. Lin, et al., “Low phase noise array-composite micromechanical wine-glass disk oscillator,” Technical Digest, IEDM, Washington, D.C., December 2005, pp. 287-290.    [2] J. Wang, et al., “1.51-GHz polydiamond micromechanical disk resonator with impedance-mismatched isolating support,” Proceedings, MEMS, Maastricht, The Netherlands, January 2004, pp. 641-644.    [3] M. Demirci and C. T.-C. Nguyen, “Mechanically corner-coupled square microresonator array for reduced series motional resistance,” IEEE/ASME J. Microelectromech. Syst., vol. 15, no. 6, pp. 1419-1436, December 2006.    [4] G. Piazza, et al., “Piezoelectric aluminum nitride vibrating contour-mode MEMS resonators,” IEEE/ASME J. Microelectromech. Syst., vol. 15, no. 6, pp. 1406-1418, December 2006.    [5] Y.-W. Lin, et al., “Series-resonant VHF micromechanical resonator reference oscillators,” IEEE Journal of Solid-State Circuits, vol. 39, no. 12, pp. 2477-2491, December 2004.    [6] J. Wang, et al., “1.156-GHz self-aligned vibrating micromechanical disk resonator,” IEEE Trans. Ultrason, Ferroelectr., Freq. Control, vol. 51, no. 12, pp. 1607-1628, December 2004.    [7] G. Piazza, P. J. Stephanou, J. M. Porter, M. B. J. Wijesundara, and A. P. Pisano, “Low motional resistance ring-shaped contour-mode aluminum nitride piezoelectric micromechanical resonators for UHF applications,” Tech. Dig., 18th IEEE Int. Conf. on MEMS, Miami Beach, Fla., Jan. 30-Feb. 3, 2005, pp. 20-23.    [8] F. D. Bannon III, J. R. Clark, and C. T.-C. Nguyen, “High frequency micromechanical filters,” IEEE J. Solid-State Circuits, vol. 35, no. 4, pp. 512-526, April 2000.    [9] S.-S. Li, Y.-W. Lin, Y. Xie, Z. Ren, and Clark T.-C. Nguyen, “Micromechanical hollow-disk ring resonators,” Proceedings, 17th Int. IEEE MEMS Conf., Maastricht, Netherlands, Jan. 25-29, 2004, pp. 821-824.    [10] S.-S. Li, Y.-W. Lin, Y. Xie, Z. Ren, and C. T.-C. Nguyen, “Small percent bandwidth design of a 431-MHZ notch-coupled micromechanical hollow-disk ring mixer-filter,” Proceedings, IEEE Int. Ultrasonics Symposium, Sep. 18-21, 2005, 1295-1298.
Recently, capacitively-driven vibrating micromechanical resonators have been demonstrated with resonance frequencies in the VHF range with Q's larger than 160,000 [1] and in the GHz range with Q's still larger than 11,000 [2], making them very attractive as on-chip frequency selecting elements for oscillators and filters in wireless communications. To date, oscillators comprised of several mechanically-coupled resonators [3] combined with sustaining transistor circuits have been demonstrated with phase noise performance commensurate with GSM cellular phone specifications for reference oscillators [1]. These oscillators owe their performance largely to the sheer Q of their constituent resonators. However, there are other applications, such as filters, where both high Q and low impedance are desirable.
Unfortunately, these two qualities have so far not been readily available simultaneously in any single CAD-definable micromechanical resonator design. So far, only capacitively-transduced resonators have achieved Q's over 50,000 at UHF frequencies [2], but with high impedance. On the other hand, piezoelectric resonators with CAD-defined frequencies have achieved impedances below 100Ω, but only with Q's in the single-digit thousands [4]. A method for combining the most attractive individual characteristics of these devices to simultaneously obtain low impedance from the piezo-device and high-Q from the capacitive ones is highly desirable.
The following U.S. patent references are related to this invention: U.S. Pat. Nos. 6,856,217; 6,985,051; 7,119,636; 7,295,088; 2006/0290449; 2006/0273867; and 2007/0046398.